As a shop owner, I often see common trends for engine failure. One of which is timing chain stretch on the GM produced LY7 designation Dual Overhead Cam 3.6 liter engine. This engine is found in the following models:

2004-2007 Buick Rendezvous

2004-2009 Cadillac CTS

2005-2007 Cadillac STS

2004-2009 Cadillac SRX

2005-2008 Buick LaCrosse

2007-2008 Saturn Outlook

2008 Buick Enclave

2008-2009 Chevy Equinox

2008-2009 Pontiac Torrent

2008-2009 Saturn Vue

2007-2009 Suzuki XL7

2008-2012 Chevy Malibu

About the LY7 V6

The LY7 engine is a high compression (10.2:1) dual overhead cam engine with dual variable valve timing. This engine has valve timing control on both intake and both exhaust camshafts and a host of sensors and mechanical parts that come along with this technology. What I find most curious is the use of 3 separate timing chains. This means you must also have three tensioners, and three sets of timing chain guides. Another interesting observation is that each camshaft has it’s own cam position sensor and VVT actuator, this means that there are 4 cam sensors and 4 VVT actuator solenoids. Making for a fairly cluttered top end. (See pic below)

Common Diagnostic Trouble Codes

P0008

Engine position performance malfunction Bank 1 (RH engine bank) This code points to a misalignment between both camshafts on this bank and the crankshaft. Most probable cause is one or more stretched timing chains – Most probable being the main timing chain.

P0009

Engine position performance malfunction Bank 2 (LH engine bank) This code points to a misalignment between both camshafts on this bank and the crankshaft. Most probable cause is one or more stretched timing chains – Most probable being the main timing chain.

P0016

Crankshaft position(CKP)/Intake camshaft(CMP) correlation Bank 1 (RH) This code points to a misalignment between the intake camshaft on bank 1 and the crankshaft. Most probable cause is one or more stretched timing chains – Most likely being the bank 1 sub chain.

P0017

Crankshaft position(CKP)/Exhaust camshaft(CMP) correlation Bank 1 (RH) This code points to a misalignment between the exhaust camshaft on bank 1 and the crankshaft. Most probable cause is one or more stretched timing chains – Most likely being the bank 1 sub chain.

P0018

Crankshaft position(CKP)/Intake camshaft(CMP) correlation Bank 2 (LH) This code points to a misalignment between the intake camshaft on bank 2 and the crankshaft. Most probable cause is one or more stretched timing chains – Most likely being the bank 1 sub chain.

P0019

Crankshaft position(CKP)/Exhaust camshaft(CMP) correlation Bank 2 (LH) This code points to a misalignment between the exhaust camshaft on bank 2 and the crankshaft. Most probable cause is one or more stretched timing chains – Most likely being the bank 1 sub chain.

These codes will often pop up together, or individually. In any case, the diagnostic procedure should be as follows for P0008 and P0009:

Connect factory equivalent scan tool to vehicle to monitor camshaft/crankshaft alignment on affected engine bank. If the affected engine bank shows an inconsistent value, it should be assumed that the timing chain and tensioners require service or replacement

Monitor camshaft position sensor signals. If any of the 4 signals is not reading or is intermittent, this sensor should be replaced and return to step 2

Special notes – A VVT actuator failure will not cause these codes to illuminate

Diagnostic procedure for P0016 P0017 P0018 and P0019

Is code P0008 or P0009 present as well? If so, timing chain replacement is likely needed.

If codes P008 and P0009 are not present, you will need to connect factory equivalent scan tool to monitor camshaft position on the affected bank. You must then actuate the correct VVT solenoid with engine at idle. If idle does not change significantly, you likely have a VVT solenoid failure.